Capacitors are an integral part of modern electronic systems such as wireless radio frequency systems and computer systems. They are used for many purposes, such as energy storage, signal coupling/decoupling, and electronic filtering. Typically, capacitors are formed of two conductive plates separated by a thin dielectric layer. The dielectric layer electrically insulates the plates from one another so that current cannot flow across them. When a voltage is applied, charge builds up on the plates and creates an electric field. The electric field prevents the charge from dissipating, which causes the charge to store in the capacitor. Although their design is simple, their integration into electronic systems proves challenging. Capacitors are bulky and occupy valuable package real estate. Furthermore, their close proximity to an integrated circuit is critical to meeting the desired system performance.
Current methods addressing these challenges have significant shortcomings. For instance, current methods mount capacitors on the top and/or bottom of a package substrate proximal to the integrated circuit. Mounting capacitors external to the package substrate substantially increases the package assembly size, which severely limits available real estate in compact electronic devices. Current methods also embed capacitors within a package substrate. Embedding the capacitors requires performance of several additional steps. For instance, an additional surface roughening step and an additional lamination step are typically required. Adding the steps reduces throughput and increases cost. Embedding the capacitors also requires purchase of a proprietary dielectric layer (e.g., 3M™ Embedded Capacitance Material (ECM)), which further increases cost. Additionally, the thickness of the proprietary dielectric layer increases the size of the embedded capacitor. Increasing the capacitor's size decreases the maximum obtainable capacitance density.